According to a photo caption on this page, the classical Greek Revival facade of the Colonial Theatre was still intact as late as 1981. By 2001, the location was occupied by a Borders book store. The caption does not say whether the building was replaced or merely remodeled.

The Colonial was actually open into the late 1960’s or early 70’s. I don’t have an exact date of closure, but I would have been about 11 or 12 at the time and I remember seeing the theater listed in the Sterling Theaters ad.

THEATER BOMBING BAFFLES SEATTLE
Police Investigate Mysterious Blast Which Rocks
City’s Business Area.
(May 12, 1928) — (A.P.)—
A theater bombing which left as clue only a sheet iron stage door riddled with scrap iron slugs and the conflicting stories of a half dozen witnesses turned into a mystery today to police who were investigating.
The bomb, manufactured with a motion picture film can and dynamite and loaded with rusty scrap iron, exploded
in the alley between the Colonial and Capitol theaters here last night while both show houses were filled. It was the sixth theater bombing here since the first of the year.
The detonation, which shattered windows in the alley and rocked the business district, alarmed theatre visitors and crowds in adjacent streets and caused a near panic in the audience of the Colonial theater.
This house was the apparent object of the bombers.
The only arrest made since the inception of the bombing campaign, was that of Thomas J. Woodhouse, a former amateur boxing champion who was taken April 23, charged with the bombing of the Embassy theater and released in $4,000 bail.
Labor disputes were given by the police and owners of the theaters as reasons for the bombings.